Production of Halogens Flashcards
What is brine?
Brine is a solution of water with a high concentration of salts - mainly sodium chloride, but also some bromine and iodine salts.
Which electrode does chlorine form at during the electrolysis of brine?
Chlorine forms at the anode.
Describe how bromine is produced from brine.
- When chlorine gas passes through brine, the chlorine displaces the bromine.
- A redox reaction occurs; Chlorine gets reduced and bromine gets oxidised.
- 2Br⁻ + Cl₂ → Br₂ + 2Cl⁻
Chlorine gas is produced industrially from the electrolysis of sodium chloride solution.
Name one natural source of sodium chloride.
[1 mark]
Rock salt / sea water / brine
Chlorine gas is produced industrially from the electrolysis of sodium chloride solution.
A student carries out the electrolysis of concentrated sodium chloride solution. Once the electrolysis is complete, they add a few a drops of universal indicator to the remaining solution.
What would you expect the student to see? Explain your answer.
[2 marks]
- The universal indicator would turn the solution blue/purple.
- The solution would be alkaline, because of the hydroxide ions left in solution.
Chlorine gas is produced industrially from the electrolysis of sodium chloride solution.
A student carries out electrolysis of dilute sodium chloride solution. They add a few drops of universal indicator to the remaining solution after the electrolysis is complete.
What would you expect the student to see? Explain your answer.
[2 marks]
- The universal indicator would turn the solution green…
- …because hydrogen ions and hydroxide ions have been discharged, leaving a neutral solution of NaCl.
Chlorine gas is produced industrially from the electrolysis of sodium chloride solution.
Chlorine gas can be used to displace iodine from brine.
State why chlorine displaces iodine from a solution of iodide ions.
[1 mark]
Chlorine is more reactive than iodine.
